Number

2,001

2,001 is a composite number, odd, a calendar year.

2,001 (two thousand one) is an odd 4-digit number. It is a composite number with 8 divisors, and factors as 3 × 23 × 29. Written other ways, in Roman numerals it is MMI and in binary, 11111010001.

Arithmetic Number Cube-Free Deficient Number Harshad / Niven Odious Number Pernicious Number Recamán's Sequence Sphenic Number Squarefree Year

Interestingness

★ ★ ★ ★ ☆

6 notable facts · grade B

1,989 1,990 1,991 1,992 1,993 1,994 1,995 1,996 1,997 1,998 1,999 2,000 2,001 2,002 2,003 2,004 2,005 2,006 2,007 2,008 2,009 2,010 2,011 2,012 2,013

less more

Notable events — 2001 AD

Jan 15 Wikipedia launches as an online encyclopedia.
Apr 1 The Netherlands becomes the first country to legalize same-sex marriage.
Sep 11 Hijackers crash four airliners into the World Trade Center, the Pentagon, and a Pennsylvania field; nearly 3,000 die.
Oct 7 A US-led coalition begins the war in Afghanistan to topple the Taliban.
Oct 23 Apple releases the first iPod.

Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0

Year facts

Year type: Common year
Standard 365-day year; not divisible by 4 (or divisible by 100 but not 400).
Days in year: 365
ISO weeks: 52
Started on: Monday
January 1, 2001
Ended on: Monday
December 31, 2001
Friday the 13ths: 2
2 Friday the 13ths this year.
Easter Sunday: April 15
Sunday, April 15, 2001
Decade: 2000s
2000–2009
Century: 21st century
2001–2100
Millennium: 3rd millennium
2001–3000
Years ago: 25
25 years before 2026.

In other calendars

Hebrew: 5761 / 5762 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 1421 / 1422 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Snake
Sexagenary cycle position 18 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 2544 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 1379 / 1380 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1993 / 1994 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1923 / 1922 Saka
Indian national calendar; year starts in March.
Japanese: Heisei 13
Reign-era counting from the start of each emperor's reign.

Properties

Parity: Odd
Digit count: 4
Digit sum: 3
Digit product: 0
Digital root: 3
Palindrome: No
Bit width: 11 bits
Reversed: 1,002
Recamán's sequence: a(3,749) = 2,001
Square (n²): 4,004,001
Cube (n³): 8,012,006,001
Divisor count: 8
σ(n) — sum of divisors: 2,880
φ(n) — Euler's totient: 1,232
Sum of prime factors: 55

Primality

Prime factorization: 3 × 23 × 29

Nearest primes: 1,999 (−2) · 2,003 (+2)

Divisors & multiples

All divisors (8)

1 · 3 · 23 · 29 · 69 · 87 · 667 · 2001

Aliquot sum (sum of proper divisors): 879

Factor pairs (a × b = 2,001)

1 × 2001

3 × 667

23 × 87

29 × 69

First multiples

2,001 · 4,002 (double) · 6,003 · 8,004 · 10,005 · 12,006 · 14,007 · 16,008 · 18,009 · 20,010

Sums & aliquot sequence

As consecutive integers: 1,000 + 1,001 666 + 667 + 668 331 + 332 + 333 + 334 + 335 + 336 76 + 77 + … + 98

Aliquot sequence: 2,001 → 879 → 297 → 183 → 65 → 19 → 1 → 0 — terminates at zero

Continued fraction of √n

√2,001 = [44; (1, 2, 1, 2, 1, 4, 1, 6, 17, 1, 2, 1, 17, 6, 1, 4, 1, 2, 1, 2, 1, 88)]

Period length 22 — the block in parentheses repeats forever.

Representations

In words: two thousand one
Ordinal: 2001st
Roman numeral: MMI
Binary: 11111010001
Octal: 3721
Hexadecimal: 0x7D1
Base64: B9E=
One's complement: 63,534 (16-bit)
Scientific notation: 2.001 × 10³
As a duration: 2,001 s = 33 minutes, 21 seconds

In other bases

ternary (3) 2202010

quaternary (4) 133101

quinary (5) 31001

senary (6) 13133

septenary (7) 5556

nonary (9) 2663

undecimal (11) 155a

duodecimal (12) 11a9

tridecimal (13) bac

tetradecimal (14) a2d

pentadecimal (15) 8d6

As an angle

2,001° = 5 × 360° + 201°

201° ≈ 3.508 rad

Compass bearing: SSW (south-southwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒌋𒁹𒁹𒁹 𒌋𒌋𒁹
Egyptian hieroglyphic: 𓆼𓆼𓏺
Greek (Milesian): ͵βαʹ
Mayan (base 20): 𝋥·𝋠·𝋡
Chinese: 二千零一
Chinese (financial): 貳仟零壹

In other modern scripts

Eastern Arabic ٢٠٠١ Devanagari २००१ Bengali ২০০১ Tamil ௨௦௦௧ Thai ๒๐๐๑ Tibetan ༢༠༠༡ Khmer ២០០១ Lao ໒໐໐໑ Burmese ၂၀၀၁

Digit at this position in famous constants

π — Pi (π): Digit 2,001 = 9
e — Euler's number (e): Digit 2,001 = 9
φ — Golden ratio (φ): Digit 2,001 = 5
√2 — Pythagoras's (√2): Digit 2,001 = 8
ln 2 — Natural log of 2: Digit 2,001 = 3
γ — Euler-Mascheroni (γ): Digit 2,001 = 7

Also seen as

Unicode codepoint

Nko Letter Dagbasinna

U+07D1

Other letter (Lo)

UTF-8 encoding: DF 91 (2 bytes).

Lookup U+07D1 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0007D1

RGB(0, 7, 209)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.209.

Address: 0.0.7.209
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.7.209

Unspecified address (0.0.0.0/8) — "this network" placeholder.

Musical pitch

Heard as a frequency, 2,001 Hz is closest to:

Concert pitch (A4 = 440 Hz): B6 (1975.5 Hz, +22¢)
Scientific pitch (C4 = 256 Hz): C7 (2048 Hz, -40¢)
Baroque pitch (A4 = 415 Hz): C7 (1974.1 Hz, +23¢)

Position in π

The digit sequence 2001 first appears in π at position 12,232 of the decimal expansion (the 12,232ordinal-suffix:nd digit after the integer 3).

Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.

Look up 2001 on Pi Search ↗